Know Your 800 Pound Gorilla, Part Two: Determining Tree Height
Foresters are usually more concerned about merchantable height in trees than the overall height, but if you are cutting trees down, you need to be able to determine how tall a tree is on a fairly regular basis. You need this information in order to tell if a tree will fall short of things you do not want to hit, such as power lines and houses. You also need to know the height to estimate whether you can handle the back lean and side lean of trees before you stick your saw in them.
A quick and fairly accurate method for height measurement is nothing more complicated than a stick in your hand for creating similar triangles. Look at the diagram above, (Click on photo to enlarge.) and note that segment ab is the same length as segment bc. Point a (A), is your eye, which must not move due to head bobbing during the measuring process. If you set up your stick properly, the distance AB will be equal to distance BC.
Back away from the tree you wish to measure, tip your head back so your eyes can easily roll to the top of the tree, extend the arm which holds your stick, and place the top of the stick at the corner of one eye.
Bring the stick up to vertical, and sight over the top of your hand to the bottom of the tree. Holding your head still, roll your eye up to the top of the stick and compare it to the top of the tree. If the tree stands taller than the stick, it can reach you, so back up and re-measure. If the stick stands taller than the tree, move in closer. When the segment bc matches BC, you are the same distance from the tree as the top of the tree is from the ground.
This is about how it looks as you move forward and back to adjust your measurement.
Next, you pace in to the tree to determine the height. Pacing is the quick, easy way to measure distances and height while working in timber. Briefly, a pace is two normal steps. Foresters alway start with the left foot, and count each pace on the right foot. Set up a measured course for determining your pace, and check yourself occasionally. Biltmore sticks, which are made for measuring merchantable height in trees, are set up to be used at 66 feet from a tree, or one chain, so every forester knows how many paces he has per chain. A course 100 feet long is also handy, and in much of the country, you can pace across twenty acres to go ten chains.
Hardwood trees usually have broad crowns, so the top center of the tree is often hard to spot. You have to be careful not to measure to the edge of a broad crown, or the height will be exaggerated greatly. Practice this a bit while the leaves are down to get a feel for it.
Firearms; Col. Jeff Cooper's Rules 1. All guns are always loaded. 2. Never let the muzzle cover anything you are not willing to destroy. 3. Keep your finger off the trigger until you are ready to shoot. 4. Be sure of your target and what lies beyond it.
Knives 1. Never cut toward yourself. 2. Always cut away from yourself. 3. Never cut yourself.
AND If you drop a knife or gun, let it fall!
Chainsaws
1. Always wear your safety gear when running your saw: hard hat, eye, face, hearing protection, cut resistant protection for your legs, heavy boots, gloves (depending on work conditions).
2. Safety devices on the saw must be in working order: front hand guard,chain brake, chain catcher, throttle lockout, and right hand guard.
3. Hold the saw on the ground or lock it between your knees for starting. No 'Drop Starts.' Set the chain brake before cranking.
4. The engine must idle reliably without turning the chain.
5. The chain must be sharpened properly, including properly set depth gauges.
6. The chain must be adjusted to remove slack and still run freely.
7. The operator must understand the forces on different parts of the bar as the saw runs: push, pull, kickback and attack.
8. Both hands must always be on the saw when the chain is running. The thumbs must be wrapped around the handles. Both feet should be firmly planted on the ground.
9. The operator must always know where the end of the bar is, and what it's doing.
10. Don't let the upper (kickback) corner of the bar contact anything when the chain is running unless the tip has been buried with the lower corner.
11. Let off of the throttle before pulling out of a pinch on the top part of the bar.
12. Make a plan for every tree you cut. Assess hazards, lean, escape routes, forward cuts, and back cuts. Evaluate the forward or backward lean, and the side lean of every tree you cut. Know your limits.
13. Clear your work area and your escape path of brush, vines, and other hazards that can trip you or catch your saw.
14. Escape from the bullseye when the tree tips. 90% of accidents happen within 12 feet of the stump. Go more than 15 feet, and stay out of the bullseye until things stop falling.
15. Keep spectators away more than twice the height of the tree in the direction it will fall.
16. Don't cut alone.
17. Keep your body and the swamper's out of the line of the bar in case of a kickback.
18. Set the brake when taking over two steps or when moving through tripping hazards. Keep your trigger finger off of the throttle when you are moving.
19. DO NOT operate a chainsaw from a ladder! Operating with your feet off the ground requires special training.
20. Do not cut above your shoulders.
21. Springpoles must be shaved on the inside of the apex between the ascending and descending sides. If the apex is higher than you shoulders, stand under the springpole and cut it low on the descending side. It will release upward, away from you.Leaning and heavily loaded poles that are too small to bore cut for a hinge should be shaved on the compressed side until they fold.
22. Do not cut a tree that is holding up a lodged tree. Do not work under a lodged tree. Think about a mouse trying to steal the cheese out of a trap.
23. Instruct your swampers and helpers to NEVER approach you from behind or the sides to within the reach of your saw when you are cutting. If you pull out of a cut with the chain running, or have a severe kickback, the swamper can be killed if he is coming up behind you!
24!! Quit When You Are Tired!
25!! Pause and review; reflect, when you are being pushed. You may be pushed into danger. Do not let pressure cause you to ignore safety rules!
Cutting dead and rotten trees is extremely risky, and your safety always comes down to basics and following the rules. Build a good hinge, even if there is just a thin shell to work with. Support the back side of the hinge with wedges if the tree is punky or hollow before you cut out the back. Don't fight side lean or back lean when cutting unsound trees. Release it quickly and get away from the stump. Tell your co-workers what your steps are before you crank your saw. You will live long.
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